Better support for parallel orders

You can now spread other orders than attacks, like move / overcharge /
build

For instance, you can select 10 engineers and then queue up building 10
mexes, when you spread the engineers will divide the orders between them

The orders are distributed according to the distance between a unit and
the destination

Fixes #27
Security fix
Update readme for latest PR
Added support for Reclaim Ground

When you give a reclaim ground order the engineers moves to the target
spot and reclaims everything around that spot.

Fits well into the ground order mechanics (move, attack, assist etc)
Security fix
Update readme for reclaim ground